Note: There is debate as to whether Saccharomyces boulardii is a subspecies of Saccharomyces cerevisiae or a separate entity. Traditional techniques cannot distinguish the two, but manufacturers of Saccharomyces boulardii claim that the two yeasts are separate species.

Background

Saccharomyces boulardii is a non-pathogenic yeast strain that has been used for treatment and prevention of diarrhea. Saccharomyces boulardii is classified as a "probiotic," or a microorganism that when ingested may have a positive influence on the host's health. Probiotics may exert their effects on the gastrointestinal system directly, or may modulate the immune system in a larger scope.

The German Commission E has approved the use of Saccharomyces boulardii for symptomatic treatment of acute diarrhea, prophylactic and symptomatic treatment of diarrhea during travel, treatment of diarrhea occurring while tube feeding, use as an adjuvant for chronic acne, for a dietary supplementation, and for a source of B vitamins and protein.

Evidence

DISCLAIMER:
These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

Diarrhea (antibiotic associated):
There is good evidence that concurrent use of Saccharomyces boulardii with antibiotic therapy reduces the incidence of developing antibiotic-associated diarrhea (AAD) (Clostridium difficile and other). In general, positive results occur only when Saccharomyces boulardii is continued for several days to several weeks after the course of antibiotics is stopped. Duplication of these results should still be attempted to confirm these findings.
Grade: A

Diarrhea in children:
Several trials suggest efficacy of Saccharomyces boulardii in the treatment of diarrhea in childhood. Further studies are still required. Use of Saccharomyces boulardii may be advantageous in both the reduction of stool frequency per day and the duration of diarrhea in this age group.
Grade: B

Antibacterial (amebiasis):
Evidence from one clinical trial supports improvement of symptoms and in patients with amebiasis treated with Saccharomyces boulardii, in addition to standard therapy. Further clinical trials are required before a firm recommendation can be made.
Grade: C

Crohn's disease:
Evidence supports mild improvement of symptoms and quality of life in patients with Crohn's disease who use Saccharomyces boulardii. More clinical trials are required before a firm recommendation can be made in this area.
Grade: C

Diarrhea (Clostridium difficile):
With the introduction of broad-spectrum antibiotics into clinical practice, Clostridium difficile infection has become a common cause of infectious diarrhea in hospitalized patients. For treatment of recurrent Clostridium difficile-associated diarrhea, Saccharomyces boulardii may decrease recurrences by about 50%, especially when combined with high-dose vancomycin. Further studies are still required.
Grade: C

Diarrhea (HIV associated):
While only small studies have been performed, treatment with Saccharomyces boulardii may improve quality of life for AIDS patients with chronic diarrhea. As fungemia has been associated with Saccharomyces boulardii administration in patients with central lines, care should be exercised in treating these patients.
Grade: C

Diarrhea (prevention during tube feeding):
Preliminary evidence supports the use of Saccharomyces boulardii for this indication. However, the role of antibiotics in the results is unclear. More studies should be performed before a strong recommendation can be made.
Grade: C

Diarrhea (traveler's):
Although evidence supports the use of Saccharomyces boulardii for other forms of diarrhea, little evidence exists to support standard treatment with Saccharomyces boulardii for traveler's diarrhea. More studies need to be performed.
Grade: C

Irritable bowel syndrome (IBS):
One clinical trial exists to support treatment with Saccharomyces boulardii for irritable bowel syndrome. Additional study is required before a firm recommendation can be made.
Grade: C

Nutritional support (premature infants):
One clinical trial exists investigating the addition of Saccharomyces boulardii to nutritional support for premature infants. No evidence was found for lipid gut absorption or increased weight gain. A benefit was noted on gut flora. Additional study is needed.
Grade: C